Backyard swimming pools could be poured concrete, above-ground, cast fiberglass, or the type that uses a vinyl liner. Each of these materials offers advantages (longevity, low installation cost, easy maintenance) and suffers from disadvantages.
Pool repair work depends on the type of pool you have, since replacing a vinyl liner is a substantially different job than resurfacing a concrete or gunite pool.
Typical costs for the various types of pools include:
Pool repair costs vary very widely by geography, the type of pool, access, and expertise.
Pool repair specialists often make up for poor pool maintenance, and are often the same company (they maintain or repair all types of pools). Use a reputable source like the List here to find above-ground pool repair companies near you, or for concrete/gunite resurfacing.
Expect to pay an hourly charge plus work-related expenses. You may be able to save money with a pool repair company by contracting for regular maintenance to prevent costly repairs.